The present invention relates to a new and improved construction of a data processing machine or data processor, especially ciphering equipment, comprising an input device for the entering of data which is to be processed. As used herein, the term "data processing machine" or "data processor" should be understood to also constituting ciphering equipment, i.e., deciphering and enciphering devices.
It is known to convert a plain text into a secret text in accordance with a Key which should remain secret for unauthorized persons. The Basic Key which is to be inserted into the enciphering device and deciphering device is periodically changed. Care must be taken to prevent third parties from improperly gaining knowledge of the Basic Key information. By resorting to suitable measures it is possible to extinguish the already inserted Basic Key information. However, it must also be insured that the Basic Key, before and during the input into the device, cannot come into the hands of unauthorized individuals. If the operator memorizes the Basic Key, then the secrecy of the Key information is substantially guaranteed. In the case of complicated Basic Keys, however, it is not possible to memorize the desired Key information. As a result, it is necessary to retain the Key information upon a record medium. The record medium must not, however, fall into the hands of unauthorized individuals. When altering the Basic Key it is necessary to enter the new Basic Key information to all cipher devices of the network. It is therefore imperative that the record medium together with the Basic Key information is available at all devices of the network.